Generally, the running speed of magnetic recording tapes which run in contact with magnetic heads of magnetic recording and reproducing apparatuses such as audio tape recorders or video tape recorders is high (e.g., 5 m/sec to 40 m/sec). For this reason, if the magnetic recording tapes are insufficiently lubricated, the surface of running magnetic tapes may be easily affected by loading between the magnetic head and tapes, causing serious problems. For example, the magnetic layer of the magnetic recording tapes may separate and wear out, the magnetic head in contact with the tape may wear out, and materials which separate from the magnetic recording medium may stick to the magnetic head.
In recognition of the problem, various attempts have been made to develop solid and liquid lubricating agents, as disclosed in U.S. Pat. Nos. 3,630,772 and 3,642,539. However, known liquid lubricating agents have the disadvantage that they are transferred from the magnetic layer to the opposite surface of the magnetic recording medium and are deteriorated by heat, water or oxygen. Solid lubricating agents have the disadvantages that the lubricating effect decreases when the agent is lost from the surface of the magnetic recording layer, resulting in an increase of dropout and a decrease in RF playback output caused by solid lubricating agent lost from the magnetic recording layer. Therefore, these liquid and solid lubricating agents are usually used in combination to compensate for each others' disadvantages. However, it has been extremely difficult to develop a magnetic recording medium using fine ferromagnetic particles and having high image qualities, in which dropout is prevented, and repeated running characteristics, reproduction of still images and RF playback output are excellent.